Axial-radial turbomachine

ABSTRACT

Axial-radial flow machine having an axial portion with at least one axial stage, a radial portion with at least one radial stage, a housing having an interior space with a dividing wall extending in a radial direction dividing the housing in an axial direction into a first partial space in which the axial portion is received and a second partial space in which the radial portion is received, and a shaft that extends in axial direction through the interior space and through the dividing wall and on which impellers of the axial portion and of the radial portion are received. A radial gap is formed between the dividing wall and a fluid guiding element of the radial portion. The fluid guiding element is axially fixed to the housing so as to be adjacent to the dividing wall. A plurality of fixing units which are distributed in circumferential direction are arranged in the radial gap, each of which fixing units axially fixes the dividing wall to the fluid guiding element.

CROSS REFERENCE TO RELATED APPLICATION

This is a U.S. national stage of application No. PCT/DE2010/050030, filed on 25 May 2010. Priority is claimed on German, Application No. 10 2009 029 647.6, filed 21 Sep. 2009, the content of which is incorporated here by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to an axial-radial flow machine having an axial portion including at least one axial stage and a radial portion including at least one radial stage.

2. Detailed Description of Prior Art

An axial-radial flow machine I as that shown in FIG. 1 has an axial portion 10 including a plurality of axial stages 11, a radial portion 20 including a plurality of radial stages 21, a housing 30 having an interior space which, by a dividing wall 40 extending in a radial direction RR of the housing 30, is divided in an axial direction AR of the housing 30 into a first partial space 31 in which the axial portion 10 is received and a second partial space 32 in which the radial portion 20 is received, and a shaft 50 that extends in axial direction AR through the interior space of the housing 30 and the dividing wall 40 thereof and on which impellers 12, 22 of the axial portion 10 and of the radial portion 20 are received.

Since the shaft 50 extends through the dividing wall 40, a rigid structure of the dividing wall 40 is undermined, which makes the dividing wall 40 more susceptible to deformations, e.g., in axial direction AR of the housing 30. For this reason, the dividing wall 40 is constructed in the prior art with a wall thickness S (see FIG. 2) that is large enough to reduce deformations of the dividing wall 40 to a permissible level.

An example of a massive or large wall thickness S such as this is shown in FIG. 2 which shows an enlarged partial view of an area A in FIG. 1. For example, a heavy-duty industrial flow machine could have an outer dimensioning in radial direction RR of about 4000 mm, and the wall thickness S (in axial direction AR of the dividing wall 40) could amount to about 500 mm.

It can easily be seen that a wall thickness increased in this way considerably increases material costs and the weight of the axial-radial flow machine 1.

SUMMARY OF THE INVENTION

It is an object of one embodiment of the invention to provide an axial-radial flow machine in which the dividing wall is reliably protected against excessive deformations in axial direction of the housing and can accordingly have a smaller wall thickness compared to the prior art.

According to one embodiment of the invention, an axial-radial flow machine has an axial portion having at least one axial stage, a radial portion having at least one radial stage, a housing having an interior space with a dividing wall extending in a radial direction of the housing axially dividing the housing into a first partial space in which the axial portion is received and a second partial space in which the radial portion is received, and a shaft that extends in axial direction through the interior space of the housing and the dividing wall thereof and on which impellers of the axial portion and of the radial portion are received, wherein a radial gap is formed between the dividing wall and a fluid guiding element of the radial portion, which fluid guiding element is axially fixed to the housing so as to be adjacent to the dividing wall, and wherein a plurality of fixing units which are distributed in circumferential direction of the housing are arranged in the radial gap, each of which fixing units axially fixes the dividing wall to the fluid guiding element.

According to one embodiment of the invention, a plurality of fixing units distributed in circumferential direction of the housing are arranged in the radial gap and each fixing unit axially fixes the dividing wall relative to the fluid guiding element. The dividing wall is reliably protected against excessive deformations in axial direction of the housing so that the dividing wall can be constructed with a reduced wall thickness compared to the prior art.

For example, in a heavy-duty industrial flow machine which could have, for example, dimensions of about 4000 mm in radial direction, a wall thickness (in axial direction) of the dividing wall can be reduced according to the invention from 500 mm to about 250 mm. Such a reduction in the wall thickness of the dividing wall can reduce the weight of the axial-radial flow machine by several tons, about 25 tons in the present example.

Further, by the reduction in the wall thickness of the dividing wall, an axial spacing of rotary bearings for the shaft carrying the impellers (which combine to form the rotor of the axial-radial flow machine) can be shortened so that the entire axial-radial flow machine can be constructed to be more compact and, in particular, axially shorter.

The fluid guiding element can be formed by a return guide or a diffuser insert of the radial portion.

According to one embodiment of the invention, the fixing units each have a projection at the dividing wall and/or at the fluid guiding element that bridges the radial gap in axial direction of the housing.

In one embodiment of the invention, the dividing wall is axially fixed to the fluid guiding element in a simple manner in the form of an axial supporting and/or axial holding of the dividing wall so that forces acting on the dividing wall axially proceeding from the axial portion in direction of the radial portion and/or proceeding from the radial portion in direction of the axial portion can be reliably absorbed.

According to one embodiment of the invention, the projections are formed in one piece with or integral with the dividing wall and/or fluid guiding element (e.g., as integral castings or lugs) or can also be mounted thereon as separate parts.

According to one embodiment of the invention, the fixing units each have a threaded bolt that extends in axial direction of the housing through the dividing wall and fluid guiding element, wherein the threaded bolt threadedly engages with at least one of either the dividing wall or the fluid guiding element.

In this case, the threaded bolt would preferably be supported axially at the respective part (dividing wall or fluid guiding element) with which it does not threadedly engage so that, in this instance also, the dividing wall would be axially fixed to the fluid guiding element in the form of an axial supporting of the dividing wall so that forces acting axially on the dividing wall proceeding from the axial portion in direction of the radial portion can be reliably absorbed.

According to one embodiment of the invention, the threaded bolt can also threadedly engage with the dividing wall as well as with the fluid guiding element so that the dividing wall is axially fixed on both sides.

According to one embodiment of the invention, each fixing unit also has a spacer sleeve arranged in the radial gap on the threaded bolt and that bridges the radial gap in axial direction of the housing.

In this case, if desirable, the threaded bolt can serve merely to fix the spacer sleeve radially, since the spacer sleeve contacts both dividing wall and fluid guiding element axially and, accordingly, axially fixes the dividing wall to the fluid guiding element in the form of an axial support of the dividing wall so that forces acting axially on the dividing wall proceeding from the axial portion in direction of the radial portion can be reliably absorbed.

According to one embodiment form of the invention, the threaded bolt is formed by a threaded screw having a shank portion which is provided with an external thread and a head portion which is formed so as to be larger than the shank portion, and the threaded bolt is inserted through a through-passage in the dividing wall proceeding from the first partial space so that the head portion is supported at the dividing wall on the first partial space side and the external thread of the shank portion engages with an internal thread in the fluid guiding element.

In this embodiment of the invention, the dividing wall is axially fixed on both sides so that forces acting on the dividing wall axially in direction of the axial portion proceeding from the radial portion and in direction of the radial portion proceeding from the axial portion can be reliably absorbed.

More precisely stated: the spacer sleeve acts as a spacer for an axial gap dimension of the radial gap on the one hand and as a support of the dividing wall against forces acting axially on the dividing wall proceeding from the axial portion in direction of the radial portion on the other hand. For axial holding of the dividing wall at the fluid guiding element, the threaded bolt acts against forces acting axially on the dividing wall proceeding from the radial portion in direction of the axial portion.

According to one embodiment of the invention, the axial-radial flow machine is formed by an axial-radial compressor.

According to this embodiment of the invention, there could be a considerable difference in pressure between the axial portion and radial portion, e.g., because a final stage of the radial portion is situated adjacent to the dividing wall. In this case, it may be that even if a final stage of the axial portion is arranged adjacent to the dividing wall, a force based on the difference in pressure acts on the dividing wall axially in direction from the radial portion to the axial portion because higher pressures can be generated by the radial portion than by the axial portion.

Because the dividing wall is axially fixed according to the invention, particularly by a threaded bolt with head portion and shank portion constructed as a threaded screw, this load situation with respect to the dividing wall is also reliably contained.

The invention will be described in more detail in the following with reference to a preferred embodiment form and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional side view of an axial-radial flow machine;

FIG. 2 is a schematic partial view of an area A of the axial-radial flow machine of FIG. 1 according to the prior art;

FIG. 3 is a schematic partial view of an area A′ of the axial-radial flow machine of FIG. 1 viewed in a first section plane;

FIG. 4 is a schematic partial view of an area A′ of the axial-radial flow machine of FIG. 1 viewed in a second section plane;

FIG. 5 are schematic perspective views with the axial-radial flow machine according to FIG. 3 and FIG. 4 in radial section in the area of the dividing wall;

FIG. 6 is a schematic partial view of an area A′ of the axial-radial flow machine of FIG. 1 showing a deformation situation of the dividing wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An axial-radial flow machine 1 according to an embodiment form of the invention will be described in the following with reference to FIG. 1 and FIGS. 3 to 6. According to one embodiment of the invention, the axial-radial flow machine 1 is formed by an axial-radial compressor (a compressor having an axial compressor and a radial compressor assembled to form a constructional unit).

The axial-radial flow machine 1 according to the invention has an axial portion 10 including a plurality of axial stages 11, a radial portion 20 including a plurality of radial stages 21, a housing 30 having an interior space which, by a dividing wall 40′ extending in a radial direction RR of the housing 30, is divided in an axial direction AR of the housing 30 into a first partial space 31 in which the axial portion 10 is received and a second partial space 32 in which the radial portion 20 is received, and a shaft 50 which extends in axial direction AR through the interior space of the housing 30 and the dividing wall 40′ thereof and on which impellers 12, 22 of the axial portion 10 and of the radial portion 20 are received.

The radial portion 20 of the axial-radial flow machine 1 according to the invention has a fluid guiding element 23 axially fixed to the housing 30 and constructed in the present instance as a return guide insert or diffuser insert for the individual stages 21 of the radial portion 20. A radial gap RS opening into a diffuser channel 24 of the radial portion 20 is formed between the dividing wall 40′ and a section of the fluid guiding element 23 of the radial portion 20 adjacent to the dividing wall 40′.

A plurality of fixing units 60 distributed in a circumferential direction UR (see FIG. 5) of the housing 30 are arranged in the radial gap RS. Each fixing unit 60 axially fixes the dividing wall 40′ to the fluid guiding element 23.

As can be seen from FIG. 3, for example, the fixing units 60 each form a projection which bridges the radial gap RS in axial direction AR of the housing 30 and which is mounted at the dividing wall 40′ and at the fluid guiding element 23 according to one embodiment and as will be described more fully in the following.

The fixing units 60 are preferably each a threaded bolt 61 formed as a threaded screw and which extends through the dividing wall 40′ and fluid guiding element 23 in axial direction AR of the housing 30, and a spacer sleeve 62 which is arranged in the radial gap RS on the threaded bolt 61 and which bridges the radial gap RS in axial direction AR of the housing 30 so that the spacer sleeve 62 contacts both the dividing wall 40′ and the fluid guiding element 23 (FIG. 4).

The threaded bolt 61 has at an end thereof a shank portion 61 a provided with an external thread and a head portion 61 b which is constructed so as to be larger than the shank portion 61 a.

As shown in FIG. 4, proceeding from the first partial space 31 (or from the axial portion 10), the threaded bolt 61 is inserted through a through-passage (not separately shown) in the dividing wall 40′ in such a way that the head portion 61 b is supported on the side of the first partial space 31 in a recess or depression (not separately shown) at the dividing wall 40′ and the external thread of the shank portion 61 a engages with an internal thread (not separately shown) in the fluid guiding element 23.

In this way, with respect to forces acting axially on the dividing wall 40′ proceeding from the radial portion 20 in direction of the axial portion 20, the threaded bolt 61 forms a tie rod that reliably absorbs these forces and accordingly prevents excessive deformation of the dividing wall 40′ axially in direction of the axial portion 10.

On the other side, the spacer sleeve 62 acts as a spacer for an axial gap dimension of the radial gap RS on the one hand and, on the other hand, ensures an axial support of the dividing wall 40′ against forces acting axially on the dividing wall 40′ proceeding from the axial portion 10 in direction of the radial portion 20 such as the forces exerted on the dividing wall 40′ by the head portion 61 b of the threaded bolt 61 when this threaded bolt 61 is tightened.

According to one embodiment of the invention twelve (12) fixing units 60 are provided as can be seen in FIG. 5; the threaded bolt is constructed, for example, as an M48 threaded screw.

According to one embodiment of the invention the axial-radial flow machine 1 constructed as axial-radial compressor is a heavy-duty industrial flow machine having, for example, an external dimensioning in radial direction RR of about 4000 mm and a wall thickness S′ of the dividing wall 40′ of about 250 mm. Accordingly, the axial-radial flow machine 1 according to the invention realizes a reduction in weight of about 25 tons compared to the prior art axial-radial flow machine which was described by way of example in the introductory part with reference to FIG. 2.

According to one embodiment of the invention, the axial-radial flow machine 1 constructed as axial-radial compressor has a difference in pressure of about 14 bar between the axial portion 10 and the radial portion 20 during operation of the axial-radial flow machine 1, the higher pressure being in the radial portion 20, for example.

This difference in pressure leads to a deformation of the dividing wall 40′ in direction of the axial portion 10. However, investigations conducted by the inventors showed that this deformation of the dividing wall 40′ could be kept within acceptable limits by the fixing units 60 and, under the same operating conditions, could even be reduced compared to a deformation of the dividing wall 40 of the prior art axial-radial flow machine described in the introductory part with reference to FIG. 2.

More precisely stated: with a pressure in the radial portion 20 higher than that in the axial portion 10 by approximately 14 bar in an axial-radial flow machine having an outer dimensioning of approximately 4000 mm, a maximum deformation path of the dividing wall 40′ toward the axial portion 10 of about 1.3 mm and a maximum tensile stress in the threaded bolt 61 of about 700 N/mm² were measured in the dividing wall 40′, having a wall thickness of 250 mm of the axial-radial flow machine 1 at an end of the dividing wall 40′ adjacent to the shaft 50.

On the other hand, with a pressure in the radial portion 20 higher than that in the axial portion 10 by approximately 14 bar in an axial-radial flow machine having an outer dimensioning of approximately 4000 mm a maximum deformation path of the dividing wall 40 toward the axial portion 10 of about 1.7 mm was measured in the dividing wall 40 having a wall thickness of 500 mm of the prior art axial-radial flow machine described above with reference to FIG. 2 at an end of the dividing wall 40 adjacent to the shaft 50.

Therefore, the maximum deformation path of the dividing wall 40′ of the axial-radial flow machine 1 according to the invention is only about 80 percent of the maximum deformation path of the dividing wall 40 of the prior art axial-radial flow machine described above with reference to FIG. 2.

Further, the inventors recognized in the course of investigations that the resulting deformation e.g., the deformation path, greatly depends upon the construction of the fluid guiding element 23 of the radial portion 20; that is, the fluid guiding element 23 should be constructed to be as stiff as possible and should be able to transmit the impinging forces into the outer area of the housing 30 as well as possible as is indicated by the deformation situation shown in FIG. 6.

Finally, the inventors also recognized in the course of investigations that the fixing units 60, particularly the spacer sleeves 62 thereof, block the flow channel formed by the radial gap RS for a working fluid to be compressed in the radial portion 20 only by about 10 percent and the efficiency of the radial portion 20 is reduced by the fixing units 60 only by a few tenths of a percent.

Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 

1-6. (canceled)
 7. Axial-radial flow machine comprising: an axial portion having at least one axial stage; a radial portion having at least one radial stage; a housing having an interior space; a dividing wall arranged in the housing that extends in a radial direction of the housing that divides the housing in an axial direction into a first partial space in which the axial portion is received and a second partial space in which the radial portion is received; a shaft that extends in axial direction through the interior space of the housing and the dividing wall on which respective impellers of the axial portion and of the radial portion are received; and a fluid guiding element of the radial portion, which is axially fixed to the housing so as to be adjacent to the dividing wall, wherein a radial gap is formed between the dividing wall and the fluid guiding element of the radial portion; and a plurality of fixing units distributed in circumferential direction of the housing and arranged in the radial gap, each of the plural fixing units axially fixing the dividing wall to the fluid guiding element.
 8. The axial-radial flow machine according to claim 7, wherein the plural fixing units each have a projection arranged at one of the dividing wall and at the fluid guiding element that bridges the radial gap in the axial direction of the housing.
 9. The axial-radial flow machine according to claim 7, wherein the plural fixing units are each configured as a threaded bolt extending in the axial direction of the housing through the dividing wall and the fluid guiding element, each threaded bolt threadedly engages with at least one of the dividing wall and the fluid guiding element.
 10. The axial-radial flow machine according to claim 9, wherein the plural fixing units each have a spacer sleeve arranged in the radial gap on the threaded bolt that bridges the radial gap in the axial direction of the housing.
 11. The axial-radial flow machine according to claim 9, wherein each threaded bolt is formed by a threaded screw having a shank portion provided with an external thread and a head portion formed so as to be larger than the shank portion, wherein each threaded bolt is inserted through a through-passage in the dividing wall proceeding from the first partial space so that the head portion is supported at the dividing wall on the side of the first partial space and the external thread of the shank portion engages with an internal thread in the fluid guiding element.
 12. The axial-radial flow machine according to claim 7, wherein the axial-radial flow machine is formed by an axial-radial compressor.
 13. The axial-radial flow machine according to claim 8, wherein the plural fixing units are each configured as a threaded bolt extending in the axial direction of the housing through the dividing wall and the fluid guiding element, each threaded bolt threadedly engages with at least one of the dividing wall and the fluid guiding element.
 14. The axial-radial flow machine according to claim 13, wherein the plural fixing units each have a spacer sleeve arranged in the radial gap on the threaded bolt that bridges the radial gap in the axial direction of the housing.
 15. The axial-radial flow machine according to claim 14, wherein each threaded bolt is formed by a threaded screw having a shank portion provided with an external thread and a head portion formed so as to be larger than the shank portion, wherein each threaded bolt is inserted through a through-passage in the dividing wall proceeding from the first partial space so that the head portion is supported at the dividing wall on the side of the first partial space and the external thread of the shank portion engages with an internal thread in the fluid guiding element.
 16. The axial-radial flow machine according to claim 7, wherein a external diameter of the axial-radial flow machine is about 4000 mm and a wall thickness of the dividing wall is less than about 500 mm.
 17. The axial-radial flow machine according to claim 7, wherein the dividing wall is about 250 mm. 